1. Field of the Invention
The present invention relates to a, preferably clear or transparent, agent in gel form for carrying out oxidative treatments in various application fields, such as, for example, cosmetics, dental technology, pharmacy and cleaning agents. is particularly well suited for use in cosmetic hair treatments, for example blonding, oxidative hair dyeing and the fixation of permanently deformed hair. The agent of the invention contains a mixture of an oxidant, at least one stabilizer, at least one specific polymer thickener and water or an aqueous solvent.
The need for such an agent will be illustrated in the following using the hair cosmetics field as an example. In the hair cosmetics field, oxidant-containing hair-treatment agents are used for various applications, hydrogen peroxide being the most commonly used oxidant contained in said agents. These oxidative hair-treatment agents play an important role in a number of cosmetic hair treatments. In blonding, for example, the hair pigments are oxidatively broken down by the action of oxidant-containing formulations which results in a brightening of the hair.
2. Description of Related Art
As a rule, blonding agents consist of two components, a hydrogen peroxide-containing formulation and a basic component. peroxodisulfates can be used to achieve a more pronounced effect. Because aqueous hydrogen peroxide solutions are very difficult to apply to the hair in a controlled manner, more or less thickened oxidizing emulsions are used. The consistency-imparting agent for such emulsions is in most cases a long-chain fatty alcohol, the emulsifiers most frequently being fatty alcohol ethoxylates, alkylsulfates, alkyl ether sulfates etc. Although these white formulations can be well localized on the hair, the ability of the hairdresser to see the condition of the hair through the formulation after said formulation has been applied to the hair is very limited. To have control of the brightening efficacy while the brightening formulation is acting on the hair, namely to be able to observe the degree of hair brightening through the applied formulation at any time, it would be desirable for the formulation to be transparent. At the same time, depending on the nature of the product, the formulation should be more or less thickened thus allowing controlled application to the hair, it should not run off the hair and thus it should come in contact with the skin only to a minor extent, which would enhance the product's acceptance and reduce the risk of skin irritations.
These properties (transparency and thickened consistency) would also be desirable for other hair treatments, for example for permanent hair deformation brought about by reducing agent-containing formulations. For lasting hair deformation, the hair is usually first treated with a deformation agent based on a keratin-reducing mercapto compound which opens the disulfide bridges of hair keratin, after which the hair is brought into the desired shape. As a rule, the deformation agent is a keratin-reducing mercapto compound, for example a salt or ester of a mercaptocarboxylic acid. The hair is then rinsed with water and oxidatively post-treated with a fixing agent. As a result, the previously opened disulfide bridges are reconnected in a new way.
In certain embodiments of the permanent hair deformation, the hair is first treated with a reducing cream, usually a thioglycolate-containing cream, and then brought into the desired shape by means of suitable auxiliary agents such as clips or a certain kind of rollers. After an exposure time which depends on the condition of the hair, the thioglycolate-based hair-deformation agent is rinsed out after which an oxidant-containing formulation is applied to the hair for fixing purposes. As a rule, the oxidant is hydrogen peroxide. The agents imparting consistency to these emulsions are in most cases long-chain fatty alcohols and the emulsifiers used cases most frequently are fatty alcohol ethoxylates, alkylsulfates and alkyl ether sulfates.
Here, too, the drawback of the emulsions is that they are not clear and transparent but white and turbid. After the formulation has been applied, therefore, the hairdresser can observe changes in the shape of the hair only to a very limited extent. To have optimum control over the hair shaping during the action of the fixing formulation on the hair, namely to be able to observe the shape of the hair through the applied formulation at any time, it would be desirable for the formulation to be transparent. At the same time, depending on the nature of the product, the formulation should here, too, be more or less thickened and be salt-resistant so that said formulation could be applied to the hair in controlled manner without it running off. It is particularly advantageous if the agent for oxidative treatment of the hair does not run off the roller at all so that the fixation can be carried out with the hair-dresser's customer sitting in the upright position and without the customary use of a washing pan during the treatment period.
Long-term thickening of oxidant-containing formulations with polymeric thickeners that form transparent gels has a destabilizing effect on the oxidant used. From a technical point of view, this necessarily leads either to poor results because of the reduced oxidant content or to dangerous deformations including destruction of the container holding these agents (known as swelling). When the most frequently employed oxidant, namely hydrogen peroxide, is used, it has thus far been necessary to adjust the pH to 2 to 3 to stabilize the hydrogen peroxide. This leads to another problem: At such a low pH, no suitable thickening polymers are thus far known that would impart to the agent sufficient viscosity and at the same time give a transparent formulation which over a period of 6 months at 40° C. would show a stable viscosity, be peroxide-resistant and have a stable pH.